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Far More Than Creatures of Habit

A biologist contends that individual tortoises have their own personalities. Such thinking is part of a controversial trend in animal behaviorism.

November 28, 2005|Louis Sahagun | Times Staff Writer

BAKER, Calif. — Among the tortoises -- out in their Mojave Desert kingdom of arroyos and burrows fringed with creosote -- the hormones were running high.

Among them was an old male courting so many females that scientists dubbed him a "cad." An unusually cooperative female they called a "hussy." Then there was a bully who thrashed competitors, but was no stud, and a huge female who showed little interest in guys.

Recent dawn-to-dusk observations have led U.S. Geological Survey biologist Kristin Berry to the provocative conclusion that Gopherus agassizii is anything but a slow, dull homebody. Tortoises don't just demonstrate behavior, she says, they show personality.

"They are not the same inside their shells; they are individuals interacting in complex communities," she said. "And there may be behavior occurring in ways we haven't yet learned to observe, or interpret. How does a tortoise exhibit joy, or play, or express frustration?"

Asking such a question was once heresy in scientific circles. But Berry and a growing number of researchers are rejecting the decades-old notion that nonhuman creatures are instinctive automatons devoid of feelings.

Where even some skeptical scientists were comfortable acknowledging that dogs, dolphins and chimpanzees show signs of personality, this new field sees a spectrum of temperament and emotions among almost all animals: octopuses and lizards, crayfish and spiders. Even fruit flies.

"Ours is a holistic view," said Andy Sih, a biologist at UC Davis, which has become a major center of research into what Sih prefers to call "behavioral syndromes in animals."

"Some scientists study bird songs, or prey behavior, or mating behavior. We are saying they are all related," he said. "Individuals who are aggressive toward other males, for example, also tend to be more aggressive in their hunting styles, and more coercive rather than nice toward females."

"It makes things a lot more complicated," he added, "but if that is the reality, you have to account for that."

His colleague, biology professor Judith Stamps, was more blunt: "Instinct is out of favor."

"This field opens us up to thinking that there are other life forms as varied as we are," she said. "Anyone with a dog or a cat at home knows this. In some places, it is important to be shy. In other places, it pays to be aggressive. Animals that live in groups might work better with a combination: some attacking, some laying low, others finding food."

That kind of talk is nothing new. Even Charles Darwin argued that emotions exist in both humans and animals.

But in the 1930s, to avoid anthropomorphizing, scientists began focusing on how animals react to stimuli, rather than broader personality traits, such as a tendency among certain alpha male tortoises to fight all day long.

All that began to change in the 1990s, when it become acceptable again, as UC Berkeley biologist Samuel D. Gosling puts it, to think of personality traits in animals as a reflection of behaviors that persist over time and in different situations.

Gosling mapped the landscape of personality in captive spotted hyenas, for example, and discovered five basic dimensions: dominance, excitability, sociability, curiosity and tolerance of humans.

"If we are to take evolution seriously," he said, "it would be a disaster to think that personality suddenly emerged when humans departed from chimpanzees."

Even colonies of brainless sea anemones fight as organized armies with distinct castes of warriors, scouts and reproducers, according to a new study by David J. Ayre from the University of Wollongong, Australia, and Richard Grosberg from UC Davis.

"Some have better memories. Some are more aggressive. Some are wimps," Grosberg said. "So, do sea anemones have personalities? Sure enough."

Implications of animal behavior that goes a step beyond what can be quantified ruffles the feathers of biologists who insist that data be repeatable in controlled conditions.

Among the skeptics is Peter Marler, professor emeritus in behavioral neurobiology at UC Davis, whom younger colleagues respectfully refer to as the alpha male of traditional animal behavior research.

"It is very difficult to develop a means of measuring personality and temperament in animals in a repeatable way," Marler said.

"So when you start talking about animal friendliness or shyness without an objective index to measure it," he added, "you're heading into the wild blue yonder."

Yet, even Marler recalled a thought-provoking study of white-crown sparrows: "We had a male who burbled a soft rendition of a particular song while going to sleep. Of course, you don't know what was going on inside his head. But it was a song he sang to a specific female he had mated with five years earlier."

Was the sparrow reliving a happy liaison? It's impossible to say, and that's why some scientists remain skeptics.

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